In many communication systems, resource allocation has a critical role in respect of transmission quality and delays in the eyes of a user (that can also be taken as a part of the transmission quality).
Especially in the systems using code division multiple access (CDMA) as a multiple access method, sharing the usually quite limited orthogonal code pools can be thought to be the one of the most important factors in using the radio interface efficiently.
The problem of the shortage of the orthogonal resources, such as codes and frequencies, becomes even worse in the future when multi-antenna techniques will be applied.
In the prior art, there are several methods for allocating transmission resources and particularly codes. One of them is a method disclosed in U.S. Ser. No. 10/324,088, where an attempt is made to solve the limitations of the code pools by using the same spreading code in a time frame for two different user devices, such as mobile phones or computers. This approach does not increase the number of codes and therefore leads easily to interference problems or even difficulties in separating users or data from each other in a CDMA system.
Another method is to introduce a secondary scrambling code. However, one problem with the secondary scrambling code is the increase in the interference that leads to a need for a higher power level.